Not Applicable
Not Applicable
1. The Field of the Invention
The present invention relates generally to footwear, and more particularly, but not necessarily entirely, to custom orthotic sandals and methods of making the same.
2. Description of Related Art
Human feet have nearly one hundred individual working parts including bones, ligaments, muscles, and tendons. To be pain free and efficient, these complex parts must exist in a specific relationship with one another. The perfect relationship of one foot structure to another may be damaged by fallen arches, loose muscles, biomechanical defects such as pronation (a rolling in of the foot), supination (a rolling out of the foot), heel spurs, bunions, or other defects. When this occurs, a person develops tired, aching feet and ankles, or pains in specific areas of the feet and ankles.
Orthotics are specialized mechanical devices used to support or supplement weakened or abnormal joints or limbs. Orthotics allow the feet and ankles to function without pain, and protect them from the repetitive stress of normal walking or sports activities. Orthotics relieve foot and ankle fatigue and pain by supporting and gently repositioning the individual components of the feet and stabilizing the ankles to allow the feet to function efficiently again.
Examples of orthotic footwear known in the art include U.S. Pat. No. 5,921,009 (granted Jul. 13, 1999 to Hice). This patent discloses a foot orthotic device having a plate and a fulcrum which can be placed in a shoe to provide the wearer with mechanical improvement of abnormal, functional and associated foot pathology. However, the orthotic device is for use with conventional shoes. Typically, orthotic devices are not suitable for use in sandals because the orthotic devices require a stable heel support to stay in contact with the foot during walking.
U.S. Pat. No. 5,555,584 (granted Sep. 17, 1996 to Moore, III et al.) discloses a custom orthotic sandal and a method for making the same. In this sandal an orthotic footbed is placed between a bottom sole and a lightweight top sole. The footbed is composed of a bag containing a gel formed of uncured silicone rubber, a cross-linking agent, a polymer and liquid plasticizer. A person puts the sandal on, and walks around on it. The gel in the footbed retains the impression of the foot. The sandal is then removed, heated to 130 degrees Fahrenheit, and allowed to cool. The gel in the footbed then becomes solid retaining the negative image of the foot. However, this invention does not allow for the adjustment of the impression in the footbed to correct abnormalities in the foot as part of a treatment program. In other words, the shape of the footbed corresponds to the shape of the user""s foot, rather than a shape required to correct an irregularity with the user""s foot. For example, if a person has flat feet, the impression of the flat feet is retained in the footbed rather than the enhanced shape required to treat flat feet. Also, the entire sandal must be heated to solidify the gel which may have detrimental effects on some of the materials in the sandals.
U.S. Pat. No. 4,503,576 (granted Mar. 12, 1985 to Brown) discloses a cork resin to form an orthotic device for use in shoes and boots. The orthotic device is heated to cause the cork to expand, a person then places a foot on the orthotic device and a plastic bag is sealed around the foot and the orthotic device. The air is then evacuated from the bag to cause the expanded cork resin to conform to the surfaces of the foot. This invention similarly does not allow for the adjustment of the orthotic device to correct abnormalities in the foot as part of a treatment program. Furthermore, the method of manufacturing this device is inconvenient since the user must be subjected to the vacuum bag procedure each time a new orthotic device is desired.
U.S. Pat. No. 4,901,390 (granted Feb. 20, 1990 to Daley) discloses a multilayer custom insole for use in ski boots and other shoes. This custom insole is composed of a polyethylene foam over a layer of extruded polyethylene. The custom insole is heated and placed into a molding platform. A person then steps into the platform and places downward force on the custom insole, which conforms to the foot of the person. The custom insole wraps around the heel and sides of the foot. The heel portion of the custom insole is then flattened and made flush with the portion corresponding to the ball of the foot. This invention suffers similar drawbacks as the preceding two inventions in that the custom insole is not modified to provide corrective characteristics, and a user must repeat the procedure of standing on a heated insole each time a new device is desired.
The prior art is thus characterized by several disadvantages that are addressed by the present invention. The present invention minimizes, and in some aspects eliminates, the above-mentioned failures, and other problems, by utilizing the methods and structural features described herein.
In view of the drawbacks inherent in the available art, it would be a significant advance in the art to provide an orthotic device which is simple in design and manufacture and capable of being used in a sandal. It would also be an advancement in the art to provide an orthotic device which is adapted for custom treatment or prevention of a foot ailment, and which can be duplicated without repeated fitting by the user.
In view of the above described state of the art, the present invention seeks to realize the following objects and advantages.
It is an object of the present invention to provide an orthotic device which is simple in design and manufacture.
It is another object of the present invention to provide an orthotic device which can be used in a sandal.
It is a further object of the present invention to provide a method of manufacturing an orthotic device such that the orthotic device can be duplicated without repeated fitting by the user.
It is an additional object of the invention, in accordance with one aspect thereof, to provide an orthotic device which is adapted for treatment or prevention of a foot ailment.
The above objects and others not specifically recited are realized in a specific illustrative embodiment of a custom fitting orthotic sandal for use in treating or preventing ailments of a user""s foot, and a method of forming the sandal. The sandal is made by first forming a negative cast of the user""s foot. Then a positive impression cast in a shape of the user""s foot is formed by filling the negative cast with plaster of paris. The positive impression cast is modified to correct for biomechanical abnormalities of the user""s foot. A moldable material is then adhered to a top surface of a sole of the sandal. Then the positive impression cast is pressed onto the moldable material to form the moldable material in a shape configured for treating or preventing ailments of the user""s foot. The moldable material is then set and assembled into an upper of the sandal. Various types of footwear can be made in this manner.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by the practice of the invention without undue experimentation. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.